depressurize the fuel like remove the fuel fail and everything that is in the way. and swap them out from there its not to hard on the 4g64. but i know on the 6g72 you have to take a ton of shitt off. upper intake mani and all that fun shit
Pretty straightforward. Start your car, then remove the MFI relay (or do anything to stop the fuel pump) and wait for the engine to die. Try cranking it for ~5 seconds to make sure you've cleared most of the fuel from the lines (there will still be some fuel in the rail so make sure you have some rags ready and waiting). The fuel rail is located on the back of the motor on the top, right behind the valve cover. Unbolt the metal fuel feed line, remove the hose clamp from the fuel return line and pull it off. Unbolt the two bolts on the fuel rail brackets that hold it in place and carefully work it out. Sometimes I remove the injectors one at a time and it makes it easier to get the rail out. Just be careful not to damage the o-rings on the injectors, it's very easy to do.